Module 1: Early Earth and the Diversification of Life Flashcards
When did Earth form? (year)
Based on what analysis?
~4.5 billion years ago
Based on analysis of slowly decaying radioisotopes.
What significant event contributed to the formation of Earth?
Nuclear fusions on the sun resulting from a supernova event
This process led to the creation of Earth.
What are the main layers of Earth that formed over time? (3)
- Metallic core
- Rocky mantle
- Lower-density, thin surface crust
Describe the conditions of early Earth.
How many years did it persist?
Inhospitable with a molten surface under intense bombardment
This state persisted for over 500 million years.
What does the intense heat and absence of liquid water indicate about early Earth?
It was a ‘sterile planet’
This means it could not support life as we know it.
The most widely used photograph of Earth, taken by the Apollo 17 mission in 1972
‘The Blue Marble’
What ancient mineral provides evidence of Earth’s early solid crust and liquid water?
Year
Ancient zircon crystals
As early as 4.3 bya
What type of isotopic evidence suggests early life on Earth (biogenic origins) 4.1 bya?
Carbon isotope ratios in zircon minerals
What type of rock provides evidence of ancient oceans and microbial life?
These rocks date back to?
Sedimentary rocks
3.86 bya
What structure in sedimentary rocks contains fossilized remains of early cells?
How old is the rock and where was it found?
Microfossil bacteria
3.45 byo rocks of the Barberton Greenstone Belt, South Africa
What geological formation in South Africa contains 3.45-billion-year-old microfossil bacteria?
Barberton Greenstone Belt
What is the approximate size of the rod-shaped microfossil bacteria found in ancient rocks?
0.7 μm
What celestial objects help determine the age of the solar system?
How old is our solar system?
meteorites
4.6 bya
What scientific technique is used to analyze ancient minerals for early Earth conditions?
Isotopic analysis
What component of zircon minerals provides clues about early life?
Graphite with biogenic carbon
Age of oldest known Earth minerals?
4.4 bya
Age of oldest known rock on Earth?
4.1 bya
If life developed from non-living matter then 4 requirements need to be fulfilled on the conditions of the early earth. (4)
- little or no free oxygen
- abundant energy source
- occurrence of chemical building blocks, dissolved inorganic minerals
- time
Why was little or no free oxygen necessary for the origin of life?
development of life from non-living matter: 4 requirements: LITTLE OR NO FREE OXYGEN
Oxygen breaks bonds (oxidizes molecules), preventing complex molecule formation.
Where did the oxygen in Earth’s atmosphere come from?
development of life from non-living matter: 4 requirements: LITTLE OR NO FREE OXYGEN
Photosynthetic organisms (e.g., cyanobacteria).
What were the possible energy sources that helped build biological molecules on early Earth? (4)
development of life from non-living matter: 4 requirements: ABUNDANT ENERGY SOURCE
- Thunderstorms
- volcanic activity
- meteorite impacts
- UV radiation
What gases were present in Earth’s early atmosphere? (5)
What gases are present in small amounts? (3)
development of life from non-living matter: 4 requirements: OCCURENCE OF CHEMICAL BUILDING BLOCKS
- CO₂
- H₂O vapor
- CO
- H₂
- N₂
with small amounts of NH₃, H₂S (Hydrogen sulfide), CH₄
Why was time an important factor in the origin of life?
development of life from non-living matter: 4 requirements: TIME
It allowed molecules to interact and form complex structures.
